Opening NHS care in England to "any willing provider" could result in the closure of local hospitals and see some patients denied care by private providers because they are expensive to treat, he said.

The Health and Social Care Bill, currently going through parliament, will see £80 billion of the NHS budget handed to GPs, enabling them to commission services.

Dr Porter told the Guardian newspaper: "Very deliberately the Government wishes to turn back the clock to the 1930s and 1940s, when there were private, charitable and co-operative providers.

"But that system failed to provide comprehensive and universal service for the citizens of this country. That's why health was nationalised. But they're proposing to go back to the days before the NHS."

He said the changes could unintentionally lead to a "patchwork provision" of healthcare, with some hospitals offering fewer services and worst-hit patients having to travel longer distances for treatment.

The doctor fears patients who are less profitable to treat, such as people attending A and E and those with chronic conditions, will be left to the care of the NHS.

But health minister Simon Burns told the newspaper: "We are modernising the NHS so we can offer patients high-quality care and improved health outcomes. Doing nothing is not an option.

"We want patients to choose the best care to suit them, but that does not mean a compromise in quality. Only those who meet rigorous quality standards will be able to provide services."